BIOLOGY - IGCSE Edexcel

Biology IGCSE Edexcel Dual Award

Section 2: Structures & Functions in Living Organisims

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  • Created by: Anna M
  • Created on: 06-01-13 12:50
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CELL STRUCTURE AND ORGANISATION
LEVELS OF ORGANISATION
MOLECULAR LEVEL
Enzymes, hormones, chlorophyll
ORGANELLE LEVEL
Nucleus, mitochondrion, chloroplast
CELLULAR LEVEL
Red blood cells, xylem cells, muscle cells
TISSUE LEVEL
A group of similar cells with the same structure and function, e.g. skin
ORGAN LEVEL
A part of the body that functions independently
SYSTEM LEVEL
A group of organs that work together to perform a common task
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CELL STRUCTURE
Nucleus controls the cell; contains genetic material.
Cytoplasm chemical reactions; contains organelles.
Mitochondrion respiration (releasing energy from food)
Cell Membrane controls what goes in and out.
Cell wall Maintains shape of cell and helps support plant.
Chloroplast Photosynthesis (making glucose from carbon dioxide and water, using
light energy).
Permanent Vacuole Contains dilute solution, cell sap, which pushes out on the cell wall
helping to support the plant.…read more

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HIGH CONCENTRATION LOW CONCENTRATION
OSMOSIS Diffusion of water
- WEAK SOLUTION (HIGH ) STRONG SOLUTION (LOW)
- Through a selectively permeable membrane.…read more

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ENZYMES
EFFECT OF TEMPERATURE
- Affected by
temperature in their ability to
break down.
- Through our controlled
assessments (using amylase)
we discovered that
- Starch breaks down
fastest at high temperature
- After 60oC it was so hot
that the enzymes denatured
EFFECT OF pH
- Affects the shape of
the enzyme molecule, which
affects the way that the
enzyme works.
- Different enzymes work
best at different pH, some at
acidic, alkaline or neutral.…read more

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Results At about 35-40°C, which is the optimum temperature, it then
decreases as denaturation occurs.
Improve?
- You can have more data collected by having more water baths prepared at
different temperatures e.g at 10°C, 20°C, 30°C etc.
- You can just add iodine solution straight to the mixtures and see how fast
the blue-black colour disappears
NUTRITION - HUMANS
Carbohydrates ­ Store energy, provide cells in our body with the energy they need:
Bread, pasta and sugary foods
Protein ­ A very important nutrient.…read more

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Water ­ Makes up for lost fluids through breathing and sweating
Drinks and some fruit and veg
Fibre ­ Keeps the large intestine healthy and prevent constipation:
Wholegrain, wholemeal and oats
PROCESSES
INGESTION Consuming something and taking it into the body
EGESTION Discharging undigested food as faeces.…read more

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Class of Examples Digestive Action Source of Where it acts in
Enzyme Enzyme the gut
Carbohydrases Pancreatic Amylase Starch ­ maltose Pancreas Small intestine
Maltase Maltose - glucose Wall of small Small intestine
intestine
Proteases Pepsin Proteins ­ Peptides Stomach wall Stomach
Trypsin Proteins ­ peptides Pancreas Small intestine
Peptidases Peptides ­ amino Wall of small Small intestine
acids intestine
Lipases Lipase Lipids ­ glycerol and Pancreas Small intestine
fatty acids
VILLI
Lining the small intestine GREATER SURFACE AREA = absorbing digested food
Each villus…read more

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By using PERISTALSIS it delivers food to your stomach
STOMACH:
Hollow organ that holds food while it is being mixed with enzymes
Cells in the lining secrete a strong acid & powerful enzymes breakdown
When the contents of the stomach are processed, they are released into the small
intestine
SMALL INTESTINE:
22-foot long muscular tube made up of three segments:
DUODENUM, JEJUNUM, ILEUM
Enzymes from PANCREAS + Bile from LIVER breakdown food
PERISTALSIS moves food through and mixes it with digestive secretions from the
·…read more

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Chlorophyll
6CO2 + 6H2O C6H12O6 + 6O2
FACTORS FOR RATE
LIGHT
Light intensity increases photosynthesis increases
Light excites chlorophyll molecules = energy for production of carbohydrates
The rate will level off as either CO2 or temperature become the limiting factor
CARBON DIOXIDE
Carbon dioxide increases photosynthesis increases
Limiting factors apply again
TEMPERATURE
Temperature increases photosynthesis increases
Enzymes work best warm = more kinetic energy to move.…read more

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GLUCOSE USES
Respiration to release energy
Joined together to make starch for storage
Proteins for growth
Seeds for fats and oils
Cellulose for cell walls
Fructose for fruits
MINERAL USE IN PLANT DEFICIENCY SIGNS
Nitrogen Making leaves Upper leaves pale green
Lower leaves pale and dead
Stunted growth ­ weak stem
Phosphorus Roots Purple leaves
Poor roots
Potassium Flowers and Fruits Poor f & f growth
Spots on leaves
Magnesium Chlorophyll Leaves turn yellow from the bottom
RESPIRATION
Respiration Is the release of energy from…read more

Comments

lwood7

These notes are amazing!

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